One factor is whether or not your allies or your enemies can communicate freely or not. Alternatively, if your allies know you're going to hide, and especially if they know where you are planning to hide, they usually can act as if they know your exact location.
–
Capt.PantslessMay 28 '13 at 15:21

1 Answer
1

Consider the spot check from anyone (friend or foe) with line of sight to be visible. Anyone with an obscured view must roll their spot against one hide check from the hiding character, which stays the same unless they perform an action (move or standard. Free actions are iffy). If you are using a map, LoS matters and circumstantial bonuses can be added to your hide check relative to the spotter. If your group doesn't use a map, you can abstractly track everyone but use a blanket circumstance modifier and unless there's a good reason why not, consider those who pass to be on one side of the room and those who fail on the other.

As far as invisibility, your allies don't instinctively know where you are. Many a game as been made hilarious by an invisible party tripping over each other, especially with mass silence cast.